Pool owners often manage their own swimming pool chemistry and equipment. There are 14.4 million residential pools and spas in the United States with 85% of pool owners managing their own pool. Managing chemistry is the largest problem for 80% of pool owners since managing a pool is confusing and time consuming and purchasing pool products is complicated. Pool owners may spend upwards of 4-6 hours on chemical management and skimming pool water. With current pool management kits, owners often manage their pool incorrectly, resulting in a cumulative $960 extra spent on pool mismanagement, 176 billion gallons of water used and misused, and 20% more energy wasted on running dirty pools. Individually, pool and spa owners spend upwards of $120/month on chemicals and, on average, their pool goes ‘green’ meaning, it grows algae or gets cloudy usually caused by a pH imbalance once a season. This algae growth and its prevention are not well understood by end-users. Users spend extra money on toxic chemicals to try to “reset” their water chemistry, energy costs because dirty water takes more energy to circulate, repairing equipment malfunctions due to dirty water, and water costs due to dumping and replacing dirty water. What is needed is a monitoring system with a replaceable reagent cartridge that will inform pool owners of the pool chemical levels and chemical adjustments needed to properly maintain their pools and spas so that they are always in proper pH balance to save money, conserve water and prevent unnecessary maintenance.